Bucking any normal person’s notion of safety, they jump fences, elude security, and clamber up cranes to balance precariously at a stomach-lurching height of more than 2,000 feet. They captured the day-and-a-half-long experience on video, giving non-daredevils at home a heart-stopping bird’s eye view of Shanghai. Excuse me while I go find my stomach, it seems to have dropped out of my body around the two-minute mark.